Since an acrylic rubber composition is excellent in heat resistance and oil resistance, it is used for hose parts and sealing articles in an engine room of a vehicle. However, there is a demand for greater heat resistance than ever because thermal conditions become severer due to recent exhaust emission controls, a trend toward higher output power of engine, and so on.
Furthermore, the hose parts, the sealing articles and others are required to have appropriate physical properties such as normal-state properties and compression set, and are recently further required to improve a vulcanization rate for a purpose of improved productivity and a scorch property for a purpose of improved processability.
In order to deal with these requirements, an acrylic rubber composition having a carboxyl group as a crosslinking site is known as a material with balanced properties of processability, a vulcanization rate, normal-state properties, compression set and heat resistance (for example, cf. Patent Document 1).
Patent Document 1: JP-A-11-100478